The performance of an intermediate-frequency amplifier

The paper gives the results of measurements carried out on an intermediate-frequency amplifier forming part of a commercial supersonic heterodyne receiver designed for broadcast reception. The amplifier is described, with special reference to the coupling transformers. Slight modifications of the circuit are necessitated by the method of test, but it is concluded that the conditions of measurement approximate closely to those of normal use. Three representative types of valves are employed in turn and it is shown that, for a prescribed standard of cut-off at the extremes of the side-bands, the amplification obtainable increases with the mutual conductance of the valves. The best type of valve to use in various circumstances is deduced from the results obtained.